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Subject: Asymptotic analysis × WGL Institute: WIAS ×

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    An asymptotic analysis for a generalized Cahn–Hilliard system with fractional operators
    (Basel : Springer, 2021) Colli, Pierluigi; Gilardi, Gianni; Sprekels, Jürgen
    In the recent paper “Well-posedness and regularity for a generalized fractional Cahn–Hilliard system” (Colli et al. in Atti Accad Naz Lincei Rend Lincei Mat Appl 30:437–478, 2019), the same authors have studied viscous and nonviscous Cahn–Hilliard systems of two operator equations in which nonlinearities of double-well type, like regular or logarithmic potentials, as well as nonsmooth potentials with indicator functions, were admitted. The operators appearing in the system equations are fractional powers A2r and B2σ (in the spectral sense) of general linear operators A and B, which are densely defined, unbounded, selfadjoint, and monotone in the Hilbert space L2(Ω), for some bounded and smooth domain Ω⊂R3, and have compact resolvents. Existence, uniqueness, and regularity results have been proved in the quoted paper. Here, in the case of the viscous system, we analyze the asymptotic behavior of the solution as the parameter σ appearing in the operator B2σ decreasingly tends to zero. We prove convergence to a phase relaxation problem at the limit, and we also investigate this limiting problem, in which an additional term containing the projection of the phase variable on the kernel of B appears.
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    Uniform asymptotic expansions for the infinite harmonic chain
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2013) Mielke, Alexander; Patz, Carsten
    We study the dispersive behavior of waves in linear oscillator chains. We show that for general general dispersions it is possible to construct an expansion such that the remainder can be estimated by 1/t uniformly in space. In particalur we give precise asymptotics for the transition from the 1/t1/2 decay of nondegenerate wave numbers to the generate 1/t1/3 decay of generate wave numbers. This involves a careful description of the oscillatory integral involving the Airy function.